F Abbas Pharmacology Malaria is a mosquitoborne infectious disease that affects humans and other animals In 2019 there were 229 million cases of malaria worldwide resulting in an estimated 409000 deaths ID: 1034663
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1. Anti-malarial drugsShaymaa F AbbasPharmacology
2. Malaria is a mosquito-borne infectious disease that affects humans and other animalsIn 2019 there were 229 million cases of malaria worldwide resulting in an estimated 409,000 deaths. Approximately 94% of the cases and deaths occurred in Sub-Saharan Africa.
3. Malaria is presented as high fever, shivering, pain in the joints, headache, repeated vomiting, generalized convulsions and coma.Symptoms only become apparent 10-35 days after being bitten by an infected mosquito.
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5. Mosquito bite—sporozoites in blood 30 minutes---liver stage 10-14 days---erythrocytic stage—merozoites and infection of other RBC– some give rise to gametocytes inside RBC(sexual form)—pick up by mosquito during blood meal—complete sexual life cycle in mosquito—sporozoites—infect human during bites
6. Human Malaria parasite is present in four species :1- P. falciparum, which has an erythrocytic cycle of 48 hours in humans produces malignant tertian feverTertian, because the fever was believed to recur every third dayMalignant, because it is the most severe form of malaria and can be fatal.
7. P. falciparum does not have a persistent exoerythrocytic stage (liver stage), so when the erythrocytic stage is eradicated, relapses do not occur.
8. P. vivax and P. ovale, produces tertian malariaHas a 48-hour erythrocytic cycle Exoerythrocytic forms (liver stage) may persist for years and cause relapsesP. malariae has a 72-hour erythrocytic cycle, causes quartan malaria and has no exoerythrocytic cycle
9. Blood Schizonticides:These drugs are so called because they kill the parasite in the blood. In infections with P. falciparum or P. malariae, which have no exoerythrocytic stage (liver stage), these drugs can result in radical cureClassification of antimalarial drugs
10. While with P. vivax or P. ovale, the drugs suppress the actual attack but exoerythrocytic forms can cause later relapses.
11. ChloroquineQuinineMefloquineHalofantrineProguanilPyrimethamineTetracyclinesBlood Schizonticides
12. This group of drugs kills the parasite at the liver stage and so called tissue schizonticides and are used for radical cure of malaria. These drugs are not required for P. falciparum or P. malariae, which have no exoerythrocytic stage1. Primaquine 2. Proguanil 3. TetracyclinesTissue Schizonticides:
13. This group of drugs acts on the sexual forms in the red blood cells (RBC) and prevent transmission of the infection because the patient becomes non infective and the parasite fails to develop in the mosquito.Gametocytocides
14. QuinineMefloquineChloroquineArtesunateArtemetherPrimaquineGametocytocides
15. The best way to treat malaria is to avoid the disease in the first place by preventing mosquito bites. Travelers to infected areas should always take simple precautions such as wearing clothes that cover much of the skin and using insect repellents in living, and especially in sleeping, since mosquitoes tend to bite between dusk and dawnBed nets sprayed with insecticides such as permethrin can also be very effectiveProphylaxis of malaria
16. Causal prophylaxis: This prevents the establishment of infection in the liver by inhibiting the pre-erythrocytic schizogony. Suppressive prophylaxis: Use of blood schizonticides suppresses the blood forms of the malaria parasite and thus protects against clinical illnessChemoprophylaxis
17. Chemoprophylactic agents are given to individuals who intend traveling to an area where malaria is endemic. Administration should start 1 week before entering the area and should be continued throughout the stay and for at least a month afterwards.No chemoprophylactic regimen is 100% effective and the choice of drug is difficult.
18. Chloroquine 300mg (base) once weekly (start one week before travel)Proguanil 200mg once daily (start one week before travel)Malarone (atovaquone and progauanil HCL), one tablet daily (start 1-2 days before travel)Doxycycline 100 mg once daily (start one week before travel)Examples of chemoprophylctic regimens
19. Chloroquine---Mechanism of action The host's hemoglobin is digested by the parasite and being transported to the parasite's food vacuole, and used as a source of amino acid.Free heme which results from digestion of hemoglobin is toxic to the parasite and need to polymerize to relatively inactive substance {hemozoin} by heme polymerase enzymeIndividual antimalarial drugs
20. Chloroquine acts by inhibiting parasitic heme polymerase Therefore by inhibiting this enzyme free heme accumulates and cause oxidative damage to the parasite membrane leading to lysis
21. Chloroquine has the ability to form complex with plasmodium DNA and interfering with DNA synthesisIt is usually given orally (half-life 50 days) and concentrated in the parasiteIn addition, it has ant rheumatic, anti-amebiasis effects and can be used in treatment of discoid lupus erythematosus
22. Gastrointestinal disturbancesDizziness, headacheCorneal deposit, retinopathyUrticariaBolus intravenous injections can cause dysrhythmias. It should be used with caution in G6PD deficient patients (although hemolysis does not occur in every deficient patients)Side effects
23. Act by binding to plasmodium DNA to prevent protein synthesis.It is given orally (half-life 10 hours) but can be given by intravenous infusion if necessary.Quinine
24. Gastrointestinal tract upsetsCinchonism: Headache, dizziness, tinnitus(ringing sound in ear), nausea, flushing, blurred vision, photophobia, diplopia With large doses, dysrhythmias, hypoglycaemia and CNS disturbances. 'Black water fever' is very occasionally associated with its administrationSide effects
25. It is a tissue schizonticideIs effective against the liver hypnozoitesShould be given for complete hepatic eradication of P vivax and P ovaleAlso active against gametocytesGiven orallyIts half-life is 36 hours.Primaquine
26. It is not well understood however, metabolite of primaquine is oxidant and lethal to the parasite.Side effects are mainly gastrointestinal tract disturbances and, with large doses, methemoglobinaemia. Hemolysis is produced in individuals with G6PD deficiency .Mechanism of action
27. They are fast-acting blood schizonticidal agents. Artesunate is water soluble and can be given orally or by intravenous, intramuscular or rectal administration.Used in combination with other drugs in resistance cases. (Artemisinin based Combination Therapy ACT, eg: Riamet (artemether plus lumefantrine)Artemisinin derivatives
28. Pyrimethamine, dapsone, sulfadoxine, ProguanilAll are folate antagonists
29. Resistance of plasmodia is now becoming a real problem in endemic areas High level of resistance is reported with P-Falciparum against chloroquine, in such condition combination of quinine, pyrimethamine and sulfonamides should be used.Another option is to use Artemisinin based Combination Therapy ACTResistance against anti malarial drugs
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